The present invention relates to a cope cutting apparatus for producing an arcuate cut having a prescribed radius and arranged at a prescribed angle relative to the longitudinal axis of a workpiece.
It is a difficult task to produce an accurate "cope" or cut surface on a structural member which is to intersect a cylindrical member. This is especially true in construction areas where hollow tubing members are to intersect at angles including compound angles. An end of the intersecting member must be cut to conform with the exterior configuration of the other member to assure that they properly abut one another. A cope must therefore be cut along the end of the intersecting member, or a hole must be formed in the intersected member. The two members will then abut at the desired angle of intersection and can be secured to one another by conventional fastening methods, such as welding.
Occasionally, on-site cope cutting has been accomplished by trial and error, using experience and best judgment as to the cope configuration needed. This method is not effective and can be time consuming if more than one cut has to be made before the final cope configuration is arrived at. Furthermore, this method is wasteful of materials when an erroneous cut can shorten a workpiece below a prescribed length and render it unusable.
Templates have been made to assure accurate cope cutting. These templates are made from detailed drawings, "developing" the proper cope line. The templates are laid on the workpiece and can be traced around or the cope can be cut directly from the template.
The template method is very costly. It usually requires a skilled person to prepare drawings and is a time-consuming task. There is a great chance for error in producing templates through complex and geommetrically imperfect measuring of curved surfaces. Not infrequently, accurate job-site cuts could prevent construction delays encountered when templates or adapters normally used are in error.
U.S. Pat. No. 2,855,043 to Opferkuch shows a compound cutting device using a band saw as the cutting tool. A fixed vise holds the material to be cut on a stationary support frame. The saw is mounted to a frame that swings about a pivot axis. The swinging saw frame is mounted to another frame that is pivoted about a secondary axis. The pivot axes of the two frames allow compound angular positioning of the saw blade and thus allow cutting of compound curvatures on the workpiece. The device is effective in producing finished workpieces having compound surface curvatures. However, the bulky arrangement of swinging frames and support frame render the device impractical as a portable cope cutter. It cannot be supported by the workpiece itself and operated therefrom.
U.S. Pat. No. 2,555,056 to Pence shows a band saw support with a saw pivotally mounted about a first vertical axis to a pair of frame members. The frame members are further pivotally mounted about a second vertical axis. The saw, however, can only be adjusted about the two vertical axes and is therefore incapable of producing a compound angular cut.
U.S. Pat. No. 2,556,670 to Ashworth shows a heavy band saw and frame pivotally mounted to an upright support pedestal. A vise on the pedestal supports the workpiece and the saw is pivoted relative to the pedestal. This device is used for cutting angular surfaces across a workpiece.
The present cope cutter is a small, uncomplicated unit used strictly for forming arcuate copes on a workpiece, especially at the ends of elongated tubing members. The device is entirely portable. It can be fixed to the workpiece and will move relative thereto regardless of the position of the workpiece.
The device includes three basic mounting elements and a band saw held thereby for pivotal movement relative to the workpiece. A clamp member engages the workpiece and holds it centered on a fixed workpiece plane relative to the remaining frame elements. A support frame is pivoted to the clamp about an axis perpendicular to the plane of the workpiece. A saw frame is pivoted to the support frame on an axis that is parallel to the workpiece plane. The saw itself is mounted to the saw frame with its cutting flight arranged parallel to the workpiece. The saw frame is pivoted at opposite sides of the workpiece to insure accuracy of the cope and compactness of the unit. The saw frame can be adjusted on the support frame to swing on a selected radius. The support frame can also be removably mounted to a table or other stationary support.